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Rosenkranz, Simon [Verfasser]. "Signal Processing for the Time-Shift Technique / Simon Rosenkranz". Berlin : epubli, 2017. http://d-nb.info/1137418338/34.
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Li, Lingxi [Verfasser], Cameron Akademischer Betreuer] Tropea y Xiaoshu [Akademischer Betreuer] [Cai. "Light Scattering of Complex Particles: Application to the Time-Shift Technique / Lingxi Li ; Cameron Tropea, Xiaoshu Cai". Darmstadt : Universitäts- und Landesbibliothek, 2020. http://d-nb.info/1222163160/34.
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Li, Lingxi [Verfasser], Cameron [Akademischer Betreuer] Tropea y Xiaoshu [Akademischer Betreuer] Cai. "Light Scattering of Complex Particles: Application to the Time-Shift Technique / Lingxi Li ; Cameron Tropea, Xiaoshu Cai". Darmstadt : Universitäts- und Landesbibliothek, 2020. http://d-nb.info/1222163160/34.
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Chen, Chi-She. "Using TD/CCSK spread spectrum technique to combat multipath interference in a multiple user system". Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179519410.
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McClelland, Anthony Francis. "Development of a novel technique for the measurement of the 1sâ†1â†/â†2 Lamb shift in high Z hydrogenic ions by Lyman #alpha#/Balmer #beta# wavelength intercomparison". Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314909.
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Soga, Diogo. "Medida de topografia de superfície usando a técnica de deslocamento de fase". Universidade de São Paulo, 2000. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-02082013-153443/.
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Neste trabalho, medimos o perfil 3D de superfícies (microtopografia) utilizando uma técnica de interferometria óptica: Phase-Shi,ftzng (Deslocamento de Fase). Utilizamos um interferômetro do tipo Twyman-Green para produzir fi.guras de interferência da superfície analisada. Essas imagens foram armazenadas usando-se uma câmera CCD ligada à um microcomputador. Para obter a microtopografia, calculamos o Mapa de Fase a partir das imagens digitalizadas usando um programa de microcomputador. Posteriormente um outro programa removeu a ambiguidade da função tangente (unwrapping), pela Técnica do Autômato Celular, usada no cáiculo do Mapa de Fase. Então efetuamos os cálculos para determinar a microtopografia da superfície. Depois fizemos a análise da microtopografia, levantando informações relevantes para a sua caracterização. Analisamos objetos com alta refletividade (espelhos planos e redes de Ronchi) e obtivemos bons resultados. Também comparamos alguns dos resultados obtidos com a técnica de Deslocamento de Fase com os resultados obtidos pela análise de Franjas de Igual Espessura.In this work we measured the 3D profile of surfaces (microtopography) using a optical interferometric technique: Phase-Shifting. We used a interferometer of type Twyman-Green to produce interferograms from analyzed surface. These images was captured using a CCD camera that was linked to a microcomputer. To obtain a microtopography, we calculated the Phase Map using the digitalized images and a software of microcomputer. Then another program removed the wrapping of tangent fuction, using the Cellular-Automata Technique, that was used to calculate the Phase Map. So we calculated the microtopography of the surface. After we did the analyses of the microtopography, find out some important informations of its description. We studied objects with high reflectivity (plane mirrors and Ronchi ruting) and we obtained good results. Also we compared some results with that obtained by analyses of Fringes of Equal Thickness\'
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Schwartz, David Aaron. "Synchronous multiprocessor realizations of shift-invariant flow graphs". Diss., Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/13021.
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Tongning, Robert-christopher. "Ralentir le déphasage des états de superposition atomiques dans un cristal de Tm3+ : YAG". Phd thesis, Université Paris Sud - Paris XI, 2014. http://tel.archives-ouvertes.fr/tel-01011160.
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Ce travail se place dans le contexte des recherches sur les mémoires quantiques pour la lumière. L'information quantique est stockée dans un état de superposition atomique, dont la durée de vie détermine le temps maximum de stockage.On s'intéresse particulièrement aux matériaux capables de capturer la lumière par excitation résonnante d'une raie d'absorption, puis de conserver l'information quantique dans un état de superposition du fondamental électronique.Dans Tm3+:YAG, l'information est enregistrée dans un état de spin nucléaire. Cependant le champ magnétique qui lève la dégénérescence nucléaire entraîne les différents spins à des vitesses de précession différentes, ce qui tend à détruire l'aimantation initiale, porteuse de l'information.Une étude quantique du cristal est réalisée lors du premier chapitre de ce manuscrit. Les trois chapitres suivants traitent des différents mécanismes conduisant au déphasage des spins nucléaires. On y trouvera différente analyses théoriques qui seront confirmées par un ensemble de résultats expérimentaux, ainsi qu'une description détaillée du dispositif expérimental. Enfin le dernier chapitre, prospectif, exploite les outils développés au cours de la thèse pour préserver les cohérences optiques. Il présente quelques résultats expérimentaux prometteurs sur l'allongement du temps de vie de ces cohérences optiques.
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Mure, Simon. "Classification non supervisée de données spatio-temporelles multidimensionnelles : Applications à l’imagerie". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI130/document.
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Avec l'augmentation considérable d'acquisitions de données temporelles dans les dernières décennies comme les systèmes GPS, les séquences vidéo ou les suivis médicaux de pathologies ; le besoin en algorithmes de traitement et d'analyse efficaces d'acquisition longitudinales n'a fait qu'augmenter. Dans cette thèse, nous proposons une extension du formalisme mean-shift, classiquement utilisé en traitement d'images, pour le groupement de séries temporelles multidimensionnelles. Nous proposons aussi un algorithme de groupement hiérarchique des séries temporelles basé sur la mesure de dynamic time warping afin de prendre en compte les déphasages temporels. Ces choix ont été motivés par la nécessité d'analyser des images acquises en imagerie par résonance magnétique sur des patients atteints de sclérose en plaques. Cette maladie est encore très méconnue tant dans sa genèse que sur les causes des handicaps qu'elle peut induire. De plus aucun traitement efficace n'est connu à l'heure actuelle. Le besoin de valider des hypothèses sur les lésions de sclérose en plaque nous a conduit à proposer des méthodes de groupement de séries temporelles ne nécessitant pas d'a priori sur le résultat final, méthodes encore peu développées en traitement d'imagesDue to the dramatic increase of longitudinal acquisitions in the past decades such as video sequences, global positioning system (GPS) tracking or medical follow-up, many applications for time-series data mining have been developed. Thus, unsupervised time-series data mining has become highly relevant with the aim to automatically detect and identify similar temporal patterns between time-series. In this work, we propose a new spatio-temporal filtering scheme based on the mean-shift procedure, a state of the art approach in the field of image processing, which clusters multivariate spatio-temporal data. We also propose a hierarchical time-series clustering algorithm based on the dynamic time warping measure that identifies similar but asynchronous temporal patterns. Our choices have been motivated by the need to analyse magnetic resonance images acquired on people affected by multiple sclerosis. The genetics and environmental factors triggering and governing the disease evolution, as well as the occurrence and evolution of individual lesions, are still mostly unknown and under intense investigation. Therefore, there is a strong need to develop new methods allowing automatic extraction and quantification of lesion characteristics. This has motivated our work on time-series clustering methods, which are not widely used in image processing yet and allow to process image sequences without prior knowledge on the final results
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Whaits, Clive Vivian. "Investigation into variable shift keying using direct sequence spread spectrum techniques". Master's thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/9565.
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Includes bibliographical references.This thesis reports the research done into a relatively unknown modulation scheme called VPSK (Variable Phase Shift Keying) and the use of DSSS (Direct Sequence Spread Spectrum) techniques to achieve carrier synchronization and hence coherent demodulation in the receiver. VPSK is a new and relatively unknown modulation scheme in which data bits are encoded using patented algorithms designed by Millerand Walker. VPSK modulation is a SSBSC (Single Sideband Suppressed Carrier) modulation scheme with good bandwidth efficiency. Data is coherently demodulated in the receiver. In existing VPSK systems, the locally generated carrier in the receiver is synchronized to an integer multiple of the symbol clock frequency to allow coherent demodulation. This coherent method of demodulation is not optimum if the channel over which information must be transmitted is a non-Gaussian channel, or has multi-path characteristics.
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Forren, Helmut R. "Multiprocessor design methodology for real-time DSP systems represented by shift-invariant flow graphs". Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/15778.
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Hong, Chun Pyo. "Implementation of recursive shift-invariant flow graphs in parallel pipelined processing environment". Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/15678.
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Flinkkilä, T. (Tapio). "Intramedullary nailing of humeral shaft fractures". Doctoral thesis, University of Oulu, 2004. http://urn.fi/urn:isbn:951427296X.
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Abstract
Although nonoperative treatment is recognized as an effective treatment method for humeral shaft fractures, it is associated with an approximately 10% risk of nonunion and long-term impairments of the shoulder joint. There is a growing interest to treat even simple humeral shaft fractures operatively to avoid these problems. Intramedullary (IM) nailing has proven to be very effective in the treatment of femoral and tibial shaft fractures and the same method has been adopted for humeral shaft fractures. However, the results regarding union rate and shoulder joint function after antegrade insertion of an IM nail have been very controversial.
The purpose of this study was to investigate fracture union, shoulder joint function and symptoms after antegrade IM nailing of humeral shaft fractures, to assess safety and results of IM nailing in pathological fractures, to evaluate the efficacy of exchange nailing and Ilizarov's technique in the treatment of nonunion after IM nailing and to find out, by comparing shoulder joint symptoms and function after antegrade IM nailing and dynamic compression (DC) plate fixation, whether antegrade access to the medullary cavity is the main reason behind shoulder joint problems.
During the years 1987-1997, 126 humeral shaft fractures were operated upon in Oulu University Hospital using antegrade IM nailing. The nonunion rate was 22% and distraction of the fracture fragments was the most important risk factor associated with nonunion. The reoperation rate, for various reasons, was 25%. Shoulder joint pain and impairment of function was present in 37% of the patients. In the treatment of 18 pathological fractures IM nailing was a rapid and safe operation, associated with good pain relief.
Exchange nailing of 13 cases of nonunion after IM nailing resulted in a union rate of 47% and this method is not useful in the humerus in contrast to tibial and femoral fractures. Permanent nonunion leaves the patient with severe impairment of the shoulder joint and a loose nail may lead to severe osteolysis of cortical bone. In complicated nonunion with poor bone quality, Ilizarov's technique, although associated with a high rate of minor complications and reoperations, worked well.
When IM nailing was compared with DC plating it was found that there were no significant differences in shoulder pain, function scores, range-of-motion and strength. Antegrade insertion of the nail, if carried out properly, is probably not the main reason for shoulder joint impairment after IM nailing.
Antegrade IM nailing of humeral shaft fractures is associated with several problems, e.g. shoulder joint impairment and difficulties in reconstruction after nonunion, and indications for this method may be exceptional, such as comminuted and pathological fractures.
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Al-Eidarous, Mustafa H. "Image processing : techniques for locating defects on shirt collars". Thesis, University of Hull, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301339.
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Jowett, Simon. "A novel photogrammetric technique using DLT to measure golf shaft dynamics". Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272754.
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Castañar, Acedo Laura. "Development and application of modern pure shift NMR techniques and improved HSQC/HSQMBC experiments". Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/300751.
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La presente tesis doctoral está centrada en el diseño y aplicación de nuevas metodologías de Resonancia Magnética Nuclear (RMN), con especial interés en (i) la obtención de espectros de RMN de protón homonuclearmente desacoplados (denominados “pure shift”) y (ii) la determinación de las constantes de acoplamiento homo- y heteronucleares en medio isotrópico y anisotrópico a través de nuevos experimentos HSQC y HSQMBC. La tesis se presenta como compendio de artículos, los cuales han sido ya publicados en revistas científicas internacionales de reconocido prestigio, de modo que todos los resultados aquí expuestos han sido previamente evaluados y analizados por investigadores expertos en el campo de la RMN y de la química.
Durante esta tesis doctoral se han diseñado una gran variedad de nuevos experimentos “pure shift”. La mayoría de ellos están basados en la técnica HOBS (Homodecoupled Band-Selective) mediante la cual es posible obtener espectros “pure shift” con una elevadísima resolución espectral manteniendo la máxima sensibilidad. El método HOBS ha sido incorporado en una gran variedad de experimentos 1D/2D convencionales los cuales han sido aplicados con éxito en la medida simple y precisa de tiempos de relajación T1 y T2 en áreas congestionadas, en la medida de contantes de acoplamiento heteronuclear a partir de multipletes simplificados, en la determinación de pequeñas diferencias de desplazamiento químico en estudios de enantiodiferenciación y en el análisis de mezclas complejas.
Por otro lado, la medición y el uso práctico de las constantes de acoplamiento ha sido un importante tema de estudio en el campo de la RMN durante muchos años, pero todavía hay una serie de problemas sin resolver. Durante esta tesis doctoral se han desarrollado nuevos experimentos HSQC y HSQMBC, que permiten llevar a cabo la medida precisa y exacta de las constantes de acoplamientos a través del análisis simple y directo de los picos y sin la necesidad de utilizar complejos post-procesamientos.The present doctoral thesis is framed within the Nuclear Magnetic Resonance (NMR) spectroscopy field, more specifically in the design of modern NMR methodologies. The research work carried out is focused on the design and application of new and modern NMR methodologies (i) to perform efficient broadband 1H homodecoupling in 1D/2D NMR experiments and (ii) to accurately determine homo- and heteronuclear coupling constants in isotropic and anisotropic conditions through improved HSQC and HSQMBC-type experiments. The thesis is presented as a compendium of publications, which have been published in prestigious peer-reviewed international scientific journals. Therefore, all the results here exposed have been previously evaluated by expert researchers in the fields of the NMR spectroscopy and chemistry. Several 1H homodecoupled NMR experiments have been developed along this doctoral thesis. Most of them are based on the Homodecoupled Band-Selective (HOBS) experiment through which it is possible to obtain homodecoupled NMR spectra with full sensitivity. HOBS methods offer a powerful and simple way to obtain high-resolved 1D and 2D NMR spectra, as efficiently demonstrated for the accurate, simple and direct measurement of T1/T2 relaxation times in overlapped regions, the determination of heteronuclear coupling constants from simplified multiplets, the determination of very small chemical shift differences with success application in enantiodifferentation studies or the analysis of highly complex mixtures. In addition, the concept of ultra-high-resolution NMR spectroscopy has been tested by combining several resolution-enhanced techniques into a single NMR experiment. On the other hand, for many years the measurement and practical use of coupling constants have been a timely topic but there are still a number of unresolved issues. Along this doctoral thesis a suite of robust HSQC and HSQMBC experiments have been developed which provide accurate and precise measurements of couplings constants through simple and direct analysis of cross-peaks without involving complex post-processing data manipulation.
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Milivojevic, Biljana. "Study of optical differential phase shift keying transmission techniques at 40 Gbit/s and beyond". kostenfrei, 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=977176231.
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Gibbs, Jonathan Alastair. "Techniques for the synchronisation and demodulation of fast frequency hopped M-ary frequency shift keying". Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293202.
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Othman, Rami. "Study of reception techniques for aeronautical telemetry modulations". Thesis, CentraleSupélec, 2019. http://www.theses.fr/2019CSUP0012.
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La télémesure aéronautique est un système utilisé pendant la phase des essais en vol qui consiste à transmettre en temps-réel les données mesurées à bord de l'avion vers une station sol par le biais d'une liaison radiofréquence. Elle est une opération critique visant à surveiller le comportement de l’avion et à garantir la sécurité du pilote. La conception et les performances des émetteurs et des récepteurs ont été améliorées au fil des années mais tout en gardant la même famille de modulation utilisée pour transmettre les données. Ces données sont modulées par une modulation à phase continue (CPM) car cette dernière possède une enveloppe complexe constante, ce qui permet l’emploi des amplificateurs de puissance dans leur régime de saturation sans distordre le signal. Cependant, contrairement aux modulations classiques, la modulation CPM n’est pas une fonction linéaire des symboles transmis, ce qui rend la tâche de la démodulation complexe surtout quand on considère des scenarii assez compliqués tels que la présence des multi trajets ou bien l’emploi d’un système multi-antennes. Dans cette thèse, on se focalise sur une modulation appelée « Shaped Offset Quadrature Phase Shift Keying telemetry group » (SOQPSK-TG) qui commence à être de plus en plus populaire en télémesure aéronautique. Cette modulation appartient à une famille particulière de CPM car elle transmet des symboles ternaires au lieu de binaires. Dans ce travail, nous développons différents algorithmes de réception pour cette modulation en considérant différents scenarii afin de garantir un lien de télémesure permanent. Les solutions proposées offrent des performances attrayantes tout en gardant une complexité raisonnable pour une implémentation en temps-réelAeronautical telemetry is a system used during the flight testing phase to monitor the behaviour of the plane by transmitting in real-time the aircraft dynamics from the aircraft to the ground station over a radio-frequency link. It is a critical process that requires highly reliable systems to ensure the pilot's safety. The design and the performance of the transmitting/ receiving equipment have been progressively upgraded over the years, and they mainly rely on continuous phase modulations (CPM) to convey the data. CPM is transmitter friendly because it has a constant complex envelope and therefore power amplifiers can be used at their saturation mode without distorting the signal. However, due to the nonlinear nature of this modulation, it can make the demodulation a hard task especially when considering complex scenarios such as the presence of multipath or the use of multiple antenna transmitters. In this PhD thesis, we focus on shaped offset quadrature phase-shift keying telemetry group (SOQPSK-TG) whose use is getting more and more popular in aeronautical. This modulation belongs to a particular CPM family since it transmits ternary symbols instead of binary ones. In this work, several reception algorithms have been developed for this modulation under different scenarios to ensure the availability of aeronautical telemetry link. These solutions offer excellent power efficiency without prohibitive complexity
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Ruflin, Justin 1981. "Analytical techniques of quality and cost : robust design, design of experiments, and the prediction of mean shift". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32782.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (leaf 50).
The quality of a product to a large extent determines the success of that product in competitive markets. Measuring and improving quality is thus a primary objective of the designer. The aim of the following work is to provide an introduction to the methods of quality optimization and to illustrate these techniques through examples. Quality is first defined and quantified. The robust design method, which is a technique that focuses on improving quality without adding cost, is then described. Particular attention is paid to experiment design, which is a major factor in the effectiveness and efficiency of the robust design process. The effect of product variability on the mean performance of a product is also explained along with the various ways that can be used to predict a shift in the mean value of the performance. Two examples are then developed. The first focuses on the application of the robust design method to illustrate the steps of the process. The second example primarily focuses on creating a comparison of the Monte Carlo, Latin Hypercube, and star pattern sampling methods on predicting mean shift. The benefits of the star pattern sampling method are apparent through the example. The error in the prediction of mean shift of the star pattern is less than 1%, and the execution time was less than one fifth the times of the Monte Carlo and Latin Hypercube methods.
by Justin Ruflin.
S.B.
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Everington, M. L. "The development of a real-time fibre-optic shaft monitor using cross-correlation techniques". Thesis, Kingston University, 2005. http://eprints.kingston.ac.uk/20366/.
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A review of non-contact rotation measurement techniques has been undertaken. A non-contact sensor utilising optical fibres for the measurement of angular frequency and torsional strain in rotating shafts has been devised and tested. Initially a system was developed capable of measuring angular frequency over a range from 5 Hz to 1000 Hz to a resolution of 1Hz by monitoring variations in the intensity of the reflected light produced by the surface profile of the rotating shaft. Signal processing techniques such as windowing and auto-correlation were investigated in detail and proved beneficial in the reduction of noise thus enhancing the visibility of the peaks in the Fast Fourier Transform (FFT) spectrum. It was found that the best results were obtained using a Hamming window. In order to identify automatically the peak in the Fourier spectrum representing the rotation rate an algorithm was devised that enabled this to be determined when the peak containing the greatest energy was not necessarily that with the lowest frequency. The addition of a second identical channel enabling data to be collected at a different point along the axis of the shaft allowed the two signals to be cross-correlated and hence changes in the relative phase of the two points deduced. A digital cross-correlation technique was implemented on a PC. From this information torques up to 0.12 Nm have been measured, with a system resolution of 0.02 Nm and a response time of 1.5 seconds.
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Jayaraman, Dheepakkumaran. "Optimization Techniques for Performance and Power Dissipation in Test and Validation". OpenSIUC, 2012. https://opensiuc.lib.siu.edu/dissertations/473.
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The high cost of chip testing makes testability an important aspect of any chip design. Two important testability considerations are addressed namely, the power consumption and test quality. The power consumption during shift is reduced by efficiently adding control logic to the design. Test quality is studied by determining the sensitization characteristics of a path to be tested. The path delay fault models have been used for the purpose of studying this problem. Another important aspect in chip design is performance validation, which is increasingly perceived as the major bottleneck in integrated circuit design. Given the synthesizable HDL code, the proposed technique will efficiently identify infeasible paths, subsequently, it determines the worst case execution time (WCET) in the HDL code.
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Bhana, Vishal Bhooshan. "Online damage detection on shafts using torsional and undersampling measurement techniques". Diss., University of Pretoria, 2013. http://hdl.handle.net/2263/25437.
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The presence of cracks in rotors is one of the most dangerous defects of rotating machinery. This can lead to catastrophic failure of the shaft and long out-of-service periods. The occurrence of a crack in a rotating shaft introduces changes in flexibilities which alters the dynamics during operation. This research deals with detecting damage in rotors by means of constantly monitoring the variation in the rotor’s dynamics during normal operating conditions. This project entails a computer finite element section as well as an experimental investigation. The flexibility in the region of the crack is different from an uncracked section. A finite element model of a shaft is built and investigated. The damaged model is the same except that the nodes in the location of the crack are not equivalenced in order to represent the crack. A simple constant cross-sectional shaft with semi-circular transverse surface cracks varying in size have been modelled on the Patran finite element software and a normal modes analysis was done using the Nastran solver. The results revealed a change in the natural frequencies due to the variation in the size of the crack. The experimental investigation involved creating sample shafts with damage positioned in them that would closely resemble what one may find in actual real-life situations and the dynamics during rotation with various torsional loadings are investigated and monitored using three methods. A fibre-optical sensor, Digital image correlation system and telemetry strain gauges were used. Undersampling techniques were used for the DIC system. Results showed that the fibre-optic sensor is by far the most favourable as it is able to detect damage under constant operation. The finite element model was updated by re-modelling the geometry, damage and material properties. The solution of the analysis matched the experimental results closely and model verification was achieved.Dissertation (MEng)--University of Pretoria, 2013.
Mechanical and Aeronautical Engineering
unrestricted
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Bovari, Emmanuel Gérard Ennio. "Economic growth, energy use and climate change : a historical and prospective approach". Thesis, Paris 1, 2020. http://www.theses.fr/2020PA01E055.
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La transition énergétique nécessite une évolution des structures productives et financières afin de développer, financer et déployer des actifs peu intensifs en carbone. S’appuyant sur une approche historique et prospective, cette thèse propose quatre essais contribuant à l’analyse de la soutenabilité d’une telle transition sous une approche structurelle. Le premier chapitre se concentre sur le rôle de l’énergie dans la croissance à long terme lors de la révolution industrielle. Nous montrons qu’une fois pris en compte le capital humain, le progrès technique et la démographie, l’énergie apparaît davantage comme un catalyseur que comme une cause profonde de la croissance moderne. Ces résultats suggèrent qu’une croissance économique non dépendante des ressources fossiles serait réalisable, mais qu’elle pourrait présenter des coûts de transition importants, notamment en raison de la dépendance au sentier technologique. Les deux chapitres suivants portent sur l’arbitrage entre stabilité financière et soutenabilité climatique au niveau mondial. Nous montrons qu’un paquet de politiques climatiques volontaristes est nécessaire pour atteindre un sentier de croissance équilibré maitrisant ces deux risques. Le dernier chapitre traite de l’attitude des citoyens à travers l’étude du financement participatif des énergies renouvelables en France. Nous montrons que le cadre d’action politique est essentiel pour le succès d’un tel instrument, qui est pertinent pour diversifier et sensibiliser la base d’investisseurs. Ces derniers seraient avant tout guidés par leurs opinions sur la durabilité du secteur, la transparence des opportunités d’investissement et la perception des risquesAchieving the energy shift requires an evolution of the structural and financial structures to develop, finance, and deploy low-carbon assets. Based on a historical and prospective approach, this PhD thesis develops four essays devoted to an analysis of the viability of the energy shift within the framework of a structural approach. The first chapter focuses on the role of energy in long-term growth focusing on the industrial revolution. We show that, once human capital, technical progress and demography are taken into account, energy appears more as a catalyst than as a root cause of modern economic growth. These results suggest that non-fossil fuel-dependent growth may be possible, but that it may have potentially large transition costs, particularly because of the dependence on technological pathways. The second and third chapters address the trade-off between financial and climate sustainability at the global level. We show that a comprehensive and proactive set of climate policies is needed to achieve a balanced growth path and to control both risks. The last chapter deals with citizens’ attitudes towards renewable energy financing through the case of crowdfunding in France, a relevant instrument to diversify the investor base and raise awareness. We show that the policy framework is essential for the success of such instruments, as investors are mainly guided by their views on the sustainability of the sector, the transparency of investment opportunities and the perception of risks
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Joyce, Christopher. "An Investigation of Technique and Equipment Factors Associated with Clubhead Speed in Golf". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2014. https://ro.ecu.edu.au/theses/1439.
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If golfers achieve long hitting distances whilst maintaining their accuracy they will gain a competitive advantage. To increase hitting distance, faster clubhead speed is required and this can potentially be achieved through a number of factors. Firstly, anthropometric factors such as height and physical factors such as trunk rotational power have been previously considered to be of importance. However, biomechanical factors such as; the X-factor (separation of the trunk-pelvis alignment when viewed in the transverse plane), have been a major focus of recent research. Further, the interaction of the golfer with the implement they hit with i.e. the golf club has also been examined in biomechanical studies. The broad aim of this doctoral research was to investigate how male high-level amateur golfers generate club head speed and this was examined in a series of five studies that examined technical and equipment factors.
The first study of this thesis (Study I) developed a valid three-dimensional Cardan / Euler model to examine the kinematics of the trunk and lower trunk during the golf swing. This validation study involved; developing and validating models and related algorithms as well as making comparisons to static and dynamic postures. It was concluded that a lateral bending / flexion-extension / axial rotation (ZYX) order of rotation was the most suitable to quantify the X-factor and lower trunk movement in the golf swing.
Previous research has shown conflicting relationships between golf swing kinematics (such as variables related to the X-factor) and clubhead speed, as well as what physical variables assist in generating clubhead speed. The second study of this thesis (Study II) had two aims.
The first aim was to determine whether significant between-club (driver and five-iron) differences existed for trunk and lower trunk kinematics as well as launch conditions. The second aim was to determine which anthropometric, physical and trunk and lower trunk kinematic variables were most strongly associated with clubhead speed. Fifteen high level amateur male golfers (2.5 ± 1.9 handicap) had their trunk and lower trunk three-dimensional kinematics data quantified using the methods developed in Study I. Nine significant (p < 0.002) between-club differences in swing kinematics were found; namely trunk and lower trunk flexion and lower trunk axial rotation, as well as ball velocity. Regression analyses explained 33.7 % and 66.7 % of the variance in clubhead speed for the driver and five-iron respectively, with both trunk and lower trunk variables showing associations with clubhead speed. No anthropometric (i.e. height) or physical (i.e. maximum trunk rotational speed) were associated with clubhead speed.
The low amount of variance explained by clubhead speed for the driver in Study II stimulated further investigation. Studies III and IV were designed to develop a method to locate the kick point during the golf swing and examine the effect of kick point location on swing parameters and their related launch conditions, respectively. Study III involved two phases, Firstly, the level of agreement between two methods of determining the static kick point was determined. This showed that an algorithm using three-dimensional locations of markers placed on the golf club was a valid method to determine the location of the static kick point. In the second phase of testing, this method was used to determine the location of the dynamic kick point during the golf swing. Excellent between-trial reliability was found for this method. Further, differences were found for the dynamic kick point location when compared to the static kick point location. The main objective of Study IV was to determine whether drivers fitted with shafts having high and low kick points would alter selected swing parameters, and related launch conditions. Twelve high level amateur male golfers (1.2 ± 1.8 handicap) had three shots analysed for each of two drivers fitted with “stiff” shafts but these drivers had differing kick point location. Stiffness profiles of these shafts were also measured. Five swing parameters and their related launch conditions were measured using a real-time launch monitor. The driver fitted with the shaft containing the high kick point displayed a more negative (steeper) angle of attack, a lower launch angle and an increased spin rate when compared to a driver fitted with a low kick point
In Study II, a relatively small amount of variance in clubhead speed was explained by the driver and it was the overall intention of the last study of this thesis (Study V) to attempt to explain more of this variance by examining both trunk and wrist kinematics. This was undertaken using two drivers containing differing kick point locations (low and high), with two separate regression models being produced. Twenty high-level amateur male golfers (1.9 ± 1.9 handicap) had their trunk and lower trunk three-dimensional kinematics data quantified as in Study II, but with the addition of a wrist segment. Four significant (p
In conclusion, the methods developed for this thesis to analyse golf swing kinematics revealed a greater insight into how highly skilled golfers produce clubhead speed. Particularly, the results from Studies II and V revealed significant associations between lower trunk related variables and clubhead speed when using different clubs (driver vs. fiveiron) and the same club fitted with two shafts of different kick point location (driver). Also, the methods developed in Studies III and IV to investigate dynamic shaft profiles (deflection) in the downswing provided possible explanations as to how shaft performance in the downswing can influence swing parameters and their related launch conditions at ball impact.
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Abaza, Mohamed. "Cooperative MIMO techniques for outdoor optical wireless communication systems". Thesis, Brest, 2015. http://www.theses.fr/2015BRES0073/document.
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Au cours de la dernière décennie, les communications optiques en espace libre (FSO) ont pris de l’ampleur dans les deux domaines académiques et industriels. L’importance de FSO s’appuie sur la possibilité de faire un système de transmission économique et écologique avec un débit élevé et sans licence à l’opposition des systèmes de transmission radiofréquences (RF). Dans la plupart des travaux antécédents sur les systèmes multi-émetteurs, seulement les canaux décorrélés ont été considérés. Un canal décorrélé nécessite un espace suffisant entre les émetteurs. Cette condition devient difficile et non-réalisable dans certaines applications. Pour cette raison, nos études se focalisent sur les performances des codes à répétition RC (Repitition Codes) et les codes OSTBC (Orthogonal Space-Time Block Codes) dans des canaux log-normaux corrélés en utilisant une modulation d’intensité et une détection directe (IM/DD). En addition, les effets des différentes conditions météorologiques sur le taux d’erreur moyen (ABER) sont étudiés. Les systèmes FSO à multi-entrées/ multi-sorties MIMO (Multiple-Input Multiple-Output) avec une modulation SSK (Space Shift Keying) ont été abordés. Les résultats obtenus montrent que la SSK est supérieure aux RC avec une modulation d’impulsion (Multiple Pulse Amplitude Modulation) pour toute efficacité spectrale égale ou supérieure à 4 bit/s/Hz. Nous avons aussi analysé les performances d’un système à sauts multiples (Multi-Hop) et des relais à transmission directe (forward relays). Nos simulations montrent que le système ainsi considéré est efficace pour atténuer les effets météorologiques et les pertes géométriques dans les systèmes de communication FSO. Nous avons montré qu’un tel système avec plusieurs entrées et une sortie (MISO, i.e. multiple-input single-output) à sauts multiples est supérieur à un système MISO avec un lien direct (direct link) avec une forte atténuation. Pour satisfaire la demande croissante des réseaux de communication à débits élevés, la communauté scientifique s'intéresse de plus en plus aux systèmes FSO avec des relais full-duplex (FD). Pour ces derniers systèmes, nous avons étudié la probabilité d'erreur moyenne (ABER) et nous avons analysé leurs performances. En considérant des différentes conditions de transmission, les performances de relais FD ont été comparées à celles d'un système avec un lien direct ou des relais half-duplex. Les résultats obtenus montrent que les relais FD ont le minimum ABER. En conséquence, les résultats obtenus dans cette thèse sont très prometteurs pour la prochaine génération de FSOFree-space optical (FSO) communication has been the subject of ongoing research activities and commercial attention in the past few years. Such attention is driven by the promise of high data rate, license-free operation, and cheap and ecological friendly means of communications alternative to congested radio frequency communications. In most previous work considering multiple transmitters, uncorrelated channel conditions have been considered. An uncorrelated channel requires sufficient spacing between transmitters. However, this can be difficult and may not be always feasible in some applications. Thereby, this thesis studies repetition codes (RCs) and orthogonal space-time block codes performance in correlated log-normal FSO channels using intensity modulation and direct detection (IM/DD). Furthermore, the effect of different weather conditions on the average bit error rate (ABER) performance of the FSO links is studied. Multiple-input multiple-output (MIMO) FSO communication systems using space shift keying (SSK) modulation have been also analyzed. Obtained results show that SSK is a potential technique for spectral efficiencies equal or greater than 4 bits/s/Hz as compared to RCs with multiple pulse amplitude modulations. The performance analysis of a multi-hop decode and forward relays for FSO communication system using IM/DD is also considered in this thesis. It is shown that multi-hop is an efficient technique to mitigate atmospheric turbulence and different weather attenuation effects and geometric losses in FSO communication systems. Our simulation results show that multiple-input single-output (MISO) multi-hop FSO systems are superior to direct link and MISO systems over links exhibiting high attenuation. Meeting the growing demand for higher data rates communication networks, a system with full-duplex (FD) relays is considered. For such a system, the outage probability and the ABER performance are analyzed under different turbulence conditions, misalignment error and path loss effects. FD relays are compared with the direct link and half-duplex relays. Obtained results show that FD relays have the lowest ABER and the outage probability as compared to the two other systems. Finally, the obtained results in this thesis are very promising towards the next generation of FSO systems
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Huang, Ming Chuan. "Comparison of shaft position estimation and correction techniques for sensorless control of surface mounted PM synchrononous motors". Thesis, Cardiff University, 2009. http://orca.cf.ac.uk/54888/.
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This thesis is a detailed study of how two error correction schemes affect the precision of shaft position estimation in state-observer techniques for sensorless control surface-mounted Permanent Magnet Synchronous Motors (PMSM), variance correction and variable PI regulation. A novel sensorless estimation technique based on Linear Kalman Filter (LKF) through constant variance correction is proposed and compared with the conventional Flux Linkage Observer (FLO) method and other state-estimation sensorless control techniques namely, Extended Kalman Filter (EKF), variable variance correction, Single Dimension Luenberger (SDL) observer and Full-Order Luenberger (FOLU) observer both through variable PI regulation. These five sensorless control techniques for PMSM are successfully implemented in the same lab-based hardware platform, i.e. full digital float-point-type DSP control inverter-fed PMSM system. Experiments are reported on each sensorless method covering position estimation, speed response, self-startup and load behaviour. Intensive analysis has also been carried out on the impact of error correction of estimated position on the steady/dynamic PMSM characteristics with different sensorless approaches. The experiment demonstrates that the novel Linear Kalman Filter can achieve the minimum average position estimation error throughout the electrical cycle of the five sensorless estimation techniques during no load operation at rated speed and also makes PMSM capable of self-startup for any initial rotor position except the dead area. A speed response experiment for LKF shows that individual speed estimation can be extracted directly from LKF state estimation for sensorless control PMSM. Experiments on the five sensorless methods proves that position error correction scheme is the dominating factor for state estimation sensorless control PMSM and better dynamic/steady control performance can be achieved using a variance correction scheme applied in EKF/LKF than with variable PI regulation applied in SDL/FOLU. The thesis also concludes that the novel Linear Kalman Filter is an optimised cost-effective sensorless estimation method for the PMSM drive industry compared with classic and Flux Linkage observers/Extended Kalman Filters.
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Haghdad, Mehdi y Kamilo Feher. "SMART ANTENNA (DIVERSITY) AND NON-FEEDBACK IF EQUALIZATION TECHNIQUES FOR LEO SATELLITE COMMUNICATIONS IN A COMPLEX INTERFERENCE ENVIRONMENT". International Foundation for Telemetering, 2003. http://hdl.handle.net/10150/605382.
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International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, NevadaAn improved performance smart diversity was invented to improve the signal performance in a combined selective fading, Additive White Gaussian Noise (AWGN), Co-channel interference (CCI) and Doppler shift environment such as the LEO satellite channel. This system is also applicable to aeronautical and telemetry channels. Smart diversity is defined here as a mechanism that selects at each moment the best branch in a n-branch diversity system based on the error quality with no default branch and no prioritization. The predominant novelty of this discovery is the introduction of multi level analog based Pseudo Error Detectors (PSED) in every branch. One of the advantages of PSED is that it is a non redundant error detection system, with no requirement for overhead and no need for additional valuable spectrum. This research was motivated by problems in LEO satellite systems due to low orbit and high relative speed with respect to the ground stations. The system is independent of the modulation techniques and is applicable to both coherent and non-coherent detections. The results from simulations using dynamic simulation techniques and hardware measurements over dynamic channels show significant improvement of both the Bit Error Rate (BER) and the Block Error Rate (BLER).
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Ayoub, Anas. "Sources laser ultrarapides performantes dans le moyen IR et le Tz". Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR044.
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La sonde atomique tomographique est un instrument d’analyse de la matière à trois dimensions avec une résolution atomique. Cet instrument s’appuie sur l’effet de champ électrique généré à l’extrémité d’un échantillon taillé sous la forme d’une aiguille nanométrique pour faire évaporer les atomes de surface qui sont collectés par un détecteur à deux dimensions. La mesure du temps de vol des ions dont l’évaporation est déclenchée par une impulsion électrique ou optique permettent de remonter à la composition chimique en plus de la localisation 3D des atomes. Dans les sondes atomiques actuelles, l’évaporation atomique est déclenchée par un laser ultrarapide émettant dans l’UV. Cependant, l’interaction de la lumière UV avec la matière induit un échauffement thermique qui limite la résolution en masse de l’instrument et empêche son exploitation pour l’analyse de matériaux fragiles comme les composants biocompatibles. Ces travaux de thèse visent à étudier des solutions pour favoriser l’évaporation rapide tout en inhibant les effets thermiques indésirables dans le cadre d’une sonde atomique laser. Notre approche consiste à exploiter des impulsions ultracourtes dans le domaine du moyen infrarouge ou du THz en raison de leur grande énergie pondéromotrice associée à une faible énergie de photon. Ce manuscrit rapporte sur le développementd’un banc de génération et caractérisation d’impulsions THz intenses. Le couplage de ces rayonnements avec une nano-pointe métallique polarisée négativement a permis de caractériser le champ proche induit à la surface de la nano-pointe qui est fortement modifié par l’effet d’antenne de cette dernière. La deuxième partie rapporte sur le développement d’une source laser ultrarapide de haute cadence accordable dans le moyen infrarouge autour de 3 mm en exploitant des fibres en verre fluoréThe atome probe tomography is an instrument for analyzing matter in three dimensions with atomic resolution. This instrument relies on the effect of an electric field generated at the end of a sample cut into the shape of a nanoscale needle to evaporate the surface atoms which are collected by a two-dimensional detector. The measurement of the time of flight of the ions whose evaporation is triggered by an electrical or optical pulse makes it possible to measure the chemical composition in addition to the 3D localization of the atoms. In current atome probes, atomic evaporation is triggered by a high-speed laser emitting in the UV. However, the interaction of UV light with matter induces thermal heating which limits the mass resolution of the instrument and prevents its use for the analysis of fragile materials such as biocompatible components. This thesis work aims to study solutions to promote rapid evaporation while inhibiting unwanted thermal effects of the laser in atome probe. Our approach consists in exploiting ultrashort pulses in the mid-infrared or THz domain due to their high ponderomotive energy associated with low photon energy. This manuscript reports on the development of a bench for the generation and characterization of intense THz pulses. Coupling these radiations with a negatively polarized metallic nanotip has made it possible to characterize the near field induced at the surface of the nanotip, which is strongly modified by the antenna effect. The second part reports on the development of an ultra-fast laser source tunable in the mid-infrared around 3 mm using fluoride glass fibers
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Wroblewski, Adam Christopher. "Health Monitoring of Cracked Rotor Systems using External Excitation Techniques". Cleveland State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=csu1228312469.
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Mourya, Rahul Kumar. "Contributions to image restoration : from numerical optimization strategies to blind deconvolution and shift-variant deblurring". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSES005/document.
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L’introduction de dégradations lors du processus de formation d’images est un phénomène inévitable: les images souffrent de flou et de la présence de bruit. Avec les progrès technologiques et les outils numériques, ces dégradations peuvent être compensées jusqu’à un certain point. Cependant, la qualité des images acquises est insuffisante pour de nombreuses applications. Cette thèse contribue au domaine de la restauration d’images. La thèse est divisée en cinq chapitres, chacun incluant une discussion détaillée sur différents aspects de la restauration d’images. La thèse commence par une présentation générale des systèmes d’imagerie et pointe les dégradations qui peuvent survenir ainsi que leurs origines. Dans certains cas, le flou peut être considéré stationnaire dans tout le champ de vue et est alors simplement modélisé par un produit de convolution. Néanmoins, dans de nombreux cas de figure, le flou est spatialement variable et sa modélisation est plus difficile, un compromis devant être réalisé entre la précision de modélisation et la complexité calculatoire. La première partie de la thèse présente une discussion détaillée sur la modélisation des flous spatialement variables et différentes approximations efficaces permettant de les simuler. Elle décrit ensuite un modèle de formation de l’image générique. Puis, la thèse montre que la restauration d’images peut s’interpréter comme un problème d’inférence bayésienne et ainsi être reformulé en un problème d’optimisation en grande dimension. La deuxième partie de la thèse considère alors la résolution de problèmes d’optimisation génériques, en grande dimension, tels que rencontrés dans de nombreux domaines applicatifs. Une nouvelle classe de méthodes d’optimisation est proposée pour la résolution des problèmes inverses en imagerie. Les algorithmes proposés sont aussi rapides que l’état de l’art (d’après plusieurs comparaisons expérimentales) tout en supprimant la difficulté du réglage de paramètres propres à l’algorithme d’optimisation, ce qui est particulièrement utile pour les utilisateurs. La troisième partie de la thèse traite du problème de la déconvolution aveugle (estimation conjointe d’un flou invariant et d’une image plus nette) et suggère différentes façons de contraindre ce problème d’estimation. Une méthode de déconvolution aveugle adaptée à la restauration d’images astronomiques est développée. Elle se base sur une décomposition de l’image en sources ponctuelles et sources étendues et alterne des étapes de restauration de l’image et d’estimation du flou. Les résultats obtenus en simulation suggèrent que la méthode peut être un bon point de départ pour le développement de traitements dédiés à l’astronomie. La dernière partie de la thèse étend les modèles de flous spatialement variables pour leur mise en oeuvre pratique. Une méthode d’estimation du flou est proposée dans une étape d’étalonnage. Elle est appliquée à un système expérimental, démontrant qu’il est possible d’imposer des contraintes de régularité et d’invariance lors de l’estimation du flou. L’inversion du flou estimé permet ensuite d’améliorer significativement la qualité des images. Les deux étapes d’estimation du flou et de restauration forment les deux briques indispensables pour mettre en oeuvre, à l’avenir, une méthode de restauration aveugle (c’est à dire, sans étalonnage préalable). La thèse se termine par une conclusion ouvrant des perspectives qui pourront être abordées lors de travaux futursDegradations of images during the acquisition process is inevitable; images suffer from blur and noise. With advances in technologies and computational tools, the degradations in the images can be avoided or corrected up to a significant level, however, the quality of acquired images is still not adequate for many applications. This calls for the development of more sophisticated digital image restoration tools. This thesis is a contribution to image restoration. The thesis is divided into five chapters, each including a detailed discussion on different aspects of image restoration. It starts with a generic overview of imaging systems, and points out the possible degradations occurring in images with their fundamental causes. In some cases the blur can be considered stationary throughout the field-of-view, and then it can be simply modeled as convolution. However, in many practical cases, the blur varies throughout the field-of-view, and thus modeling the blur is not simple considering the accuracy and the computational effort. The first part of this thesis presents a detailed discussion on modeling of shift-variant blur and its fast approximations, and then it describes a generic image formation model. Subsequently, the thesis shows how an image restoration problem, can be seen as a Bayesian inference problem, and then how it turns into a large-scale numerical optimization problem. Thus, the second part of the thesis considers a generic optimization problem that is applicable to many domains, and then proposes a class of new optimization algorithms for solving inverse problems in imaging. The proposed algorithms are as fast as the state-of-the-art algorithms (verified by several numerical experiments), but without any hassle of parameter tuning, which is a great relief for users. The third part of the thesis presents an in depth discussion on the shift-invariant blind image deblurring problem suggesting different ways to reduce the ill-posedness of the problem, and then proposes a blind image deblurring method using an image decomposition for restoration of astronomical images. The proposed method is based on an alternating estimation approach. The restoration results on synthetic astronomical scenes are promising, suggesting that the proposed method is a good candidate for astronomical applications after certain modifications and improvements. The last part of the thesis extends the ideas of the shift-variant blur model presented in the first part. This part gives a detailed description of a flexible approximation of shift-variant blur with its implementational aspects and computational cost. This part presents a shift-variant image deblurring method with some illustrations on synthetically blurred images, and then it shows how the characteristics of shift-variant blur due to optical aberrations can be exploited for PSF estimation methods. This part describes a PSF calibration method for a simple experimental camera suffering from optical aberration, and then shows results on shift-variant image deblurring of the images captured by the same experimental camera. The results are promising, and suggest that the two steps can be used to achieve shift-variant blind image deblurring, the long-term goal of this thesis. The thesis ends with the conclusions and suggestions for future works in continuation of the current work
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Hidrovo, Chavez Carlos Hiller. "Development of a fluorescence based optical diagnostics technique and investigation of particle ingestion and accumulation in the contact region of rotating shaft seals". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/28233.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.Includes bibliographical references (leaves 200-203).
Seals are, arguably, the single most important component in any complex machine. Seals maintain lubrication and prevent the ingestion of contaminants into bearing surfaces, allowing high tolerance components to function reliably. Consequently, the performance of seals can be directly linked to the performance, life span and reliability of virtually all equipment of any complexity. Investigation of the failure of these components due to external contaminants ingestion and lubrication breakdown is of particular importance. To facilitate the study of the lubricant behavior, a unique non-invasive two-dimensional optical technique which allows instantaneous measurement of the lubricating film thickness and temperature was developed. The technique is based on the use of Laser Induced Fluorescence (LIF). In its simplest form, LIF has a number of limitations and shortcomings. In the past, it has been mostly used as a tracer for qualitative purposes, seeing limited use as a quantitative tool. This stems primarily from the dependence of fluorescence on exciting light intensity, rendering the emission useful only as a tagging indicator. In order to use the fluorescent emission as a signal for highly accurate quantitative measurements, a dual emission ratiometric approach that suppresses excitation intensity information was implemented. The concept is to use one emission as the carrier of the desired information, while the other emission provides the excitation intensity information.
(cont.) Film temperature measurements require optically thin conditions and a strong dependence on temperature of one fluorescent emission. Film thickness measurements were performed using an innovative approach that requires an optically thick fluorescence system that portrays reabsorption of one fluorescent emission. Alluding to this requisite, the new technique was termed Emission Reabsorption Laser Induced Fluorescence (ERLIF) and along with the temperature measurement approach they are presented and discussed in the first part of this thesis. The second part of this thesis addresses the particulars of the investigation carried out on rotating shaft seals, in specific on the particle ingestion mechanics that lead to the failure of these components. A correlation between dust particle ingestion and the hydrodynamically generated "reverse pumping" mechanism was established through a joint schedule of experimental testing and analytical/numerical modeling.
by Carlos Hiller Hidrovo Chávez.
Ph.D.
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Baroni, Axelle. "Modélisation du couplage sol-fluide pour la sismique entre puits". Châtenay-Malabry, Ecole centrale de Paris, 1996. http://www.theses.fr/1996ECAP0515.
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La propagation des ondes élastiques entre deux puits de forage est un problème complexe du fait de la génération d'ondes guidées: ces ondes à la fois présentes dans le puits émetteur et le puits récepteur, contiennent une information que l'on ne sait pas encore réellement exploiter. Modéliser une expérience de sismique entre puits permet de quantifier la génération, la diffraction et la radiation de ces ondes: c'est ce que propose le mémoire de cette thèse, à l'aide d'une technique hybride de sous-structuration dans laquelle les deux puits sont traités indépendamment: on couple pour cela des méthodes numériques et analytiques. On se ramène à un problème dont l'inconnue (déplacement et vecteur contrainte) est une fonction définie sur les interfaces du domaine de calcul, et qui nécessite le calcul préalable d'operateurs obtenus par la résolution de problèmes auxiliaires posés dans chaque sous-structure (on utilisera les équations intégrales de frontière dans les milieux élastiques, et une formulation variationnelle dans les milieux fluides). Une hypothèse supplémentaire d'axisymetrie permet une réduction du nombre de calculs par une expansion selon l'angle azimutal en mode de Fourier. Les résultats obtenus sont qualitativement et quantitativement satisfaisants
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Du, Preez Johannes. "An investigation into OFDM as a suitable modulation tecnique for an acoustic underwater modem". Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71806.
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Thesis (MScEng)--Stellenbosch University, 2012.ENGLISH ABSTRACT: This thesis investigates orthogonal frequency division multiplexing (OFDM) as a viable modulation technique for an ultrasonic acoustic underwater modem. The underwater environment provides a challenging setting for acoustic communications. Long delay spreads due to multipath propagation, severe Doppler frequency shifts, frequency dependent absorption and very limited bandwidth are but some of the challenges to overcome. OFDM essentially provides the parallel transmission of symbols in the frequency domain by simultaneously modulating many closely spaced orthogonal subcarriers. The resulting long parallel symbol rate together with the cyclic extension of symbols render the signal robust against intersymbol interference (ISI) caused by multipath propagation. Intercarrier interference (ICI) between the overlapping frequency responses of subcarriers is mitigated by their property of orthogonality. Doppler spread contributes to the loss of orthogonality and can result in severe ICI. A method of measuring the Doppler shift by means of including a preamble and postamble symbol with each data frame is proposed. The detected frequency offset is corrected by resampling the frame at the desired sample rate. Not only do the ambles serve as a mechanism for timing and frequency synchronisation, but they are also applied in the channel estimation process. The equalisation of channel response is required for the coherent demodulation of the received symbols. An investigation into different phase shift keying (PSK) and quadrature amplitude modulation (QAM) constellations reveal optimal arrangements for minimal symbol errors. The optimised QAM constellations do not lend themselves to Gray-coding, so that an efficient interleaving scheme is needed to mitigate the non-uniform distribution of bit errors among symbol errors. Forward error correction is provided via a Bose Chaudhuri Hocquenghem (BCH) block code. Variable code rates, together with the ability to switch between different constellations, enable the modem to perform so-called variable modulation in an attempt to maximise the throughput under specific channel conditions. The modulation/demodulation scheme is wholly defined in software as to provide flexibility and facilitate experimentation with different signal processing methods. The accompanying hardware platform allows for the transmission of a pre-generated signal and the recording of a received signal for off-line processing. The prototype design serves as a proof of concept and thus provides only simplex communication. Field tests over limited distances demonstrate the successful operation of the prototype modem. We conclude that OFDM is indeed a suitable modulation technique for acoustic underwater communication.
AFRIKAANSE OPSOMMING: Hierdie tesis ondersoek die toepassing van ortogonale frekwensiedeling multipleksering (OFDM) as modulasie tegniek op ʼn onderwater kommunikasie modem. Die onderwater omgewing bied vele uitdagings vir akoestiese kommunikasie. Lang vertraging-verstrooiings as gevolg van multipad voortplanting, Doppler frekwensieskuif, frekwensieafhanklike absorpsie, en beperkte bandwydte is van die uitdagings wat oorkom moet word. In essensie bied OFDM die parallelle versending van ʼn aantal simbole deur die gelyktydige modulasie van verskeie nou-gespasieerde subdraers in die frekwensiegebied. Die gevolglike lang parallelle simboolperiodes, tesame met die sikliese uitbreiding van simbole, verleen immuniteit teen intersimbool steurnisse (ISI) wat ontstaan as gevolg van multipad voortplanting. Die ortogonaliteit van naburige draers in die frekwensiegebied beperk interdraer steuring (ICI) tussen hul oorvleuelende frekwensie weergawes. Doppler frekwensieskuif kan egter lei tot die verlies aan ortogonaliteit en bydra tot ernstige interdraer steurings. ʼn Metode wat gebruik maak van aanhef en slot simbole, ingesluit by elke raam, word voorgestel om die Dopplerskuif te meet. Die bepaalde frekwensieafset word gekorrigeer deur die monstertempo van die raam aan te pas na die verlangde tempo. Buiten die tyd- en frekwensie-sinkronisasie funksies van die aanhef en slot simbole, speel dit ook ʼn belangrike rol in die ontrekking van die frekwensie weergawe van die kanaal. Die effening van die kanaal se frekwensieweergawe is noodsaaklik vir die koherente demodulasie van die ontvangde simbole. ʼn Ondersoek na verskillende fase verskuif sleuteling (PSK) en kwadratuur amplitude modulasie (QAM) konstellasies het optimale rangskikkings opgelewer vir minimale simboolfoute. Hierdie optimale QAM konstellasies verleen hulself egter nie na Gray-kodering nie. ʼn Effektiewe invlegtegniek is nodig om die nie-uniforme verspreiding van bisfoute tussen simboolfoute te beperk. Fout korrigering funksionaliteit word gebied deur ʼn Bose Chaudhuri Hocquenghem (BCH) blokkode. Verstelbare koderingstempo’s en die vermoë om tussen verskillende konstellasies te skakel, stel die modem in staat om sogenaamde verstelbare modulasie te gebruik in ʼn poging om die data deurset te optimeer onder spesifieke kanaal kondisies. Die modulasie en demodulasie skema is volledig in sagteware gedefinieer. Dit verleen buigbaarheid en vergemaklik eksperimentering met verskeie seinverwerkingstegnieke. Die meegaande hardeware platvorm stel die modem in staat om vooraf opgewekte seine uit te saai en rou ontvangde siene op te neem vir na-tydse verwerking. Die prototipe ontwerp dien as ʼn konseptuele bewys en bied dus slegs simplekse kommunikasie. Die suksesvolle werking van die modem is gedemonstreer deur toetsing oor beperkte afstande. Hieruit word afgelei dat OFDM inderdaad geskik is vir akoestiese onderwater kommunikasie.
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Carli, Daniel Michelon de. "GERAÇÃO PROCEDURAL DE CENÁRIOS 3D DE CÂNIONS COM FOCO EM JOGOS DIGITAIS". Universidade Federal de Santa Maria, 2012. http://repositorio.ufsm.br/handle/1/5394.
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This Master s thesis proposes a non-assisted procedural method for 3D canyons scenes
generation based on techniques of computer graphics, computer vision and graph search
algorithm. In order to define all the features to be reproduced in our scenes, we have
analyzed several images of real canyons and have categorized them in two canyon features
models: a recursive and an ordinary one. The proposed approach manipulates a
heightmap, created using Perlin noise, in order to imitate the geological features formation
previously analyzed. Several parametrizations are used to guide and constraint the
generation of terrains, canyons features, course of river, plain areas, soft slope regions,
cliffs and plateaus. This work also uses the Mean Shift algorithm as mechanism of segmentation
to define regions of interest. A binary mask, with plain areas, is defined based
on a threshold operation by a given data set provided by the Mean Shift algorithm. Thereafter
a connected-component labeling algorithm is executed using the previously binary
mask. This algorithm finds all plains centroids. Right after that, the Dijkstra s algorithm
is performed in order to connect all plain areas, creating a valid path between the centroids.
The Dijkstra s algorithm is executed again to define the river s course. Finally, a
Gaussian smoothing operation is applied to interpolate the soft slope regions. The combination
of all those techniques produces as a result automatically generated feature-rich
canyons.Esta dissertação propõe um método procedural não assistido, baseado em técnicas de computação gráfica, visão computacional e busca em grafos, para a geração de cenários 3D de cânions com foco em jogos digitais. Para definir as características a serem reproduzidas, foram analisadas diversas imagens de cânions reais chegando-se em dois modelos, um comum e outro recursivo. A abordagem proposta manipula um reticulado gerado com ruído de Perlin, moldando assim as características inerentes a essa formação geológica. São levadas em conta as diversas parametrizações necessárias para permitir que o algoritmo construa cânions com curso de rio, áreas de planícies, regiões de encosta suave, estruturas de penhascos e, por fim, planaltos nas regiões mais altas. Para atingir o resultado final, o trabalho utiliza o algoritmo Mean Shift como mecanismo de segmentação, definindo dados e regiões de interesse. Munido dos dados do algoritmo de clusterizacao, é definido um limiar para a criação de uma máscara binária com a definição das planícies. Em um segundo momento, um algoritmo de rotulação de componentes conectados é executado, extraindo-se os centróides de cada planície. Por sua vez, o algoritmo de Dijkstra encaixa-se na definição de rotas que conectam estas planícies. O algoritmo de Dijkstra é, então, executado novamente, tendo por base uma função de custo de inclinação, para definir o curso do rio. Por fim, uma filtragem espacial baseada em um filtro Gaussiano é aplicada para interpolar as regiões de encostas de declive suave. A combinação dessas técnicas gera terrenos com grande variabilidade e com as características inerentes à formação geológica de cânions.
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Dudal, Clément. "Forme d'onde multiporteuse pour de la diffusion par satellite haute capacité". Phd thesis, Toulouse, INPT, 2012. http://oatao.univ-toulouse.fr/8342/1/dudal.pdf.
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Cette thèse se concentre sur l’amélioration conjointe de l'efficacité spectrale et de l'efficacité en puissance de schémas de transmission par satellite. L’émergence de nouveaux services et l'augmentation du nombre d’acteurs dans le domaine nécessitent de disposer de débits de plus en plus importants avec des ressources de plus en plus limitées. Les progrès réalisés ces dernières années sur la technologie embarquée et dans le domaine des communications numériques permettent de considérer des schémas de transmission à plus haute efficacité spectrale et en puissance. Cependant, l’enjeu majeur des schémas de transmission proposes actuellement reste de rentabiliser les ressources disponibles. L’étude développée dans cette thèse explore les possibilités d’amélioration conjointe de l’efficacité spectrale et de l’efficacité en puissance en proposant la combinaison de la modulation Cyclic Code-Shift-Keying (CCSK), dont l’efficacité en puissance augmente avec l’élévation du degré de la modulation, avec une technique de multiplexage par codage de type Code-Division Multiplexing (CDM) pour pallier la dégradation de l’efficacité spectrale liée à l’étalement du spectre induit par la modulation CCSK. Deux approches basées sur l’utilisation de séquences de Gold de longueur N sont définies: Une approche multi-flux avec un décodeur sphérique optimal en réception. La complexité liée à l’optimalité du décodeur conduit à des valeurs d'efficacité spectrale limitées mais l’étude analytique des performances, vérifiée par des simulations, montre une augmentation de l'efficacité en puissance avec l'efficacité spectrale. Une approche mono-flux justifiée par l’apparition de redondance dans les motifs résultant du multiplexage des séquences. L’approche mono-flux propose des valeurs d’efficacité spectrale équivalente aux schémas retenus dans le standard DVB-S2 avec une amélioration de l’efficacité en puissance à partir d’un certain seuil de rapport signal à bruit par rapport à ces schémas. Par la suite, l'étude porte sur la transposition de plusieurs symboles de modulation sur les porteuses d’un système OFDM et sur les bénéfices et avantages d’une telle approche. Elle se conclut sur l’apport d’un codage canal basé sur des codes par bloc non binaires Reed-Solomon et LDPC. La forme d’onde proposée offre des points de fonctionnement à haute efficacité spectrale et haute efficacité en puissance avec des perspectives intéressantes. Dans le contexte actuel, son application reste limitée par ses fluctuations d’amplitude mais est envisageable dans un contexte de transmission multiporteuse, comme attendu dans les années à venir.
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Hussain, Zahir M. "Adaptive instantaneous frequency estimation: Techniques and algorithms". Thesis, Queensland University of Technology, 2002. https://eprints.qut.edu.au/36137/7/36137_Digitised%20Thesis.pdf.
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This thesis deals with the problem of the instantaneous frequency (IF) estimation of sinusoidal signals. This topic plays significant role in signal processing and communications.
Depending on the type of the signal, two major approaches are considered. For IF estimation of single-tone or digitally-modulated sinusoidal signals (like frequency shift keying signals) the approach of digital phase-locked loops (DPLLs) is considered, and this is Part-I of this thesis. For FM signals the approach of time-frequency analysis is considered, and this is Part-II of the thesis.
In part-I we have utilized sinusoidal DPLLs with non-uniform sampling scheme as this type is widely used in communication systems. The digital tanlock loop (DTL) has introduced significant advantages over other existing DPLLs. In the last 10 years many efforts have been made to improve DTL performance. However, this loop and all of its modifications utilizes Hilbert transformer (HT) to produce a signal-independent 90-degree phase-shifted version of the input signal. Hilbert transformer can be realized approximately using a finite impulse response (FIR) digital filter. This realization introduces further complexity in the loop in addition to approximations and frequency limitations on the input signal. We have tried to avoid practical difficulties associated with the conventional tanlock scheme while keeping its advantages. A time-delay is utilized in the tanlock scheme of DTL to produce a signal-dependent phase shift. This gave rise to the time-delay digital tanlock loop (TDTL). Fixed point theorems are used to analyze the behavior of the new loop. As such TDTL combines the two major approaches in DPLLs: the non-linear approach of sinusoidal DPLL based on fixed point analysis, and the linear tanlock approach based on the arctan phase detection. TDTL preserves the main advantages of the DTL despite its reduced structure. An application of TDTL in FSK demodulation is also considered. This idea of replacing HT by a time-delay may be of interest in other signal processing systems. Hence we have analyzed and compared the behaviors of the HT and the time-delay in the presence of additive Gaussian noise.
Based on the above analysis, the behavior of the first and second-order TDTLs has been analyzed in additive Gaussian noise.
Since DPLLs need time for locking, they are normally not efficient in tracking the continuously changing frequencies of non-stationary signals, i.e. signals with time-varying spectra. Nonstationary signals are of importance in synthetic and real life applications. An example is the frequency-modulated (FM) signals widely used in communication systems. Part-II of this thesis is dedicated for the IF estimation of non-stationary signals. For such signals the classical spectral techniques break down, due to the time-varying nature of their spectra, and more advanced techniques should be utilized.
For the purpose of instantaneous frequency estimation of non-stationary signals there are two major approaches: parametric and non-parametric. We chose the non-parametric approach which is based on time-frequency analysis. This approach is computationally less expensive and more effective in dealing with multicomponent signals, which are the main aim of this part of the thesis.
A time-frequency distribution (TFD) of a signal is a two-dimensional transformation of the signal to the time-frequency domain. Multicomponent signals can be identified by multiple energy peaks in the time-frequency domain. Many real life and synthetic signals are of multicomponent nature and there is little in the literature concerning IF estimation of such signals. This is why we have concentrated on multicomponent signals in Part-H.
An adaptive algorithm for IF estimation using the quadratic time-frequency distributions has been analyzed. A class of time-frequency distributions that are more suitable for this purpose has been proposed. The kernels of this class are time-only or one-dimensional, rather than the time-lag (two-dimensional) kernels. Hence this class has been named as the T -class. If the parameters of these TFDs are properly chosen, they are more efficient than the existing fixed-kernel TFDs in terms of resolution (energy concentration around the IF) and artifacts reduction. The T-distributions has been used in the IF adaptive algorithm and proved to be efficient in tracking rapidly changing frequencies. They also enables direct amplitude estimation for the components of a multicomponent
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Natter, Bernard. "Etude de l'usure et de l'ecaillage de pieces d'un reacteur d'avion par la technique d'activation en couches superficielles". Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13223.
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Utilisation de la technique d'activation en couches superficielles. Formation du radioelement cobalt 56 par reaction nucleaire. Etude du profil de concentration et mesure in situ d'usure et d'ecaillage (cas des pompes a carburant). Aspects metallurgiques. Application a l'industrie aeronautique
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Palosaari, K. (Kari). "Quantitative and semiquantitative imaging techniques in detecting joint inflammation in patients with rheumatoid arthritis:phase-shift water-fat MRI method for fat suppression at 0.23 T, contrast-enhanced dynamic and static MRI, and quantitative 99mTc-nanocolloid scintigraphy". Doctoral thesis, University of Oulu, 2008. http://urn.fi/urn:isbn:9789514288623.
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Abstract
The purpose of this study was to evaluate the value of 0.23T low-field magnetic resonance imaging (MRI) and nanocolloid (NC) scintigraphy in assessing joint pathology associated with rheumatoid arthritis (RA).
Fat suppression methods combined with contrast media enhancement aid in distinguishing enhancing inflamed tissue from the surrounding fat, especially in the imaging of arthritic joints. The feasibility and image quality of a phase-shift water-fat MRI method for fat suppression at low-field 0.23T open configuration MR scanner was evaluated. The technique was combined with contrast-enhanced imaging to assess the conspicuity of synovial hypertrophy in the joints of 30 RA patients. Improved conspicuity and delineation of synovitis was detected with this method. However, because of a great amount of manual post processing, future development is needed to make this method more feasible.
Contrast-enhanced MRI and NC scintigraphy may provide objective and quantitative information about the inflammatory activity in arthritic joints. The value of quantitative and semiquantitative measures of inflammation derived from NC scintigraphy and low-field MRI of the wrist joint of 28 early RA patients was evaluated. Furthermore, it was investigated whether these parameters have predictive value of further erosive development during two years of follow-up.
Strong correlations were detected between the NC scintigraphy and MRI measures, and these parameters were associated with laboratory markers of inflammation. During the two-year follow-up, the initial MRI and NC scintigraphy measures were closely related with the progression of wrist joint erosions.
Small erosive-like bone defects can occasionally be found in wrist MRI of patients without clinically overt arthritis. The prevalence of these lesions was studied in bilateral wrist MRI examinations of 31 healthy persons. Small lesions resembling erosions were detected in 14 out of 31 subjects. Altogether 24 of the 930 wrist bones evaluated showed such lesions (3%). Thus small changes resembling erosions can be found in the wrist MRI of healthy subjects; the significance of these findings must always be interpreted with reference to the clinical picture.
In conclusion, early RA patients with high local inflammatory activity, as detected by NC scintigraphy and MRI are at risk of developing further bone damage. Furthermore, in the follow-up of early RA patients, if clinically sustained response is not achieved, these methods help to identify patients who need more intensive drug treatment.
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Dompierre, Julien. "Équations intégrales en axisymétrie généralisée : application à la sismique entre puits". Châtenay-Malabry, Ecole centrale de Paris, 1993. http://www.theses.fr/1993ECAP0295.
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On présente une méthode de calcul pour simuler la propagation d'ondes acoustiques et élastiques générées par une source dans un puits vertical au sein d'un sol multicouche. Ce problème est décomposé en sous-problèmes sur chaque sous-domaine du sol et du fluide. Sur chaque sous-domaine, on doit résoudre une équation d'ondes (Helmholtz ou Navier) et satisfaire des conditions de radiation à l'infini et des conditions aux limites de continuité (interaction sol-fluide). Pour cela, on utilise la méthode des éléments finis de frontière. On suppose que la géométrie du problème est axisymétrique et on décomposé les équations intégrales en séries de Fourier. A basses fréquences, seuls les premiers modes de Fourier interviennent. Les simulations montrent la présence d'une onde de tube, mode propre guide du puits
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Sazzad, TM Shahriar. "An automated approach to identify nongrowing follicles using digitized images of type P63 histopathology ovarian slides". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2017. https://ro.ecu.edu.au/theses/2032.
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Many developing countries are still facing challenges with limited access to fertility health services. Women face problems in conceiving due to many factors such as increasing age. In vitro fertilization (IVF) treatments can assist these women but are considered too expensive. Medical pathology laboratories are searching for novel technologies that can improve microscopic slide testing of female ovarian reproductive tissues. Current electronic methods for the assessment of human ovaries are not suitable for analysis of ovarian reproductive tissues. Ultrasound method cannot be used to identify small ovarian Non-Growing Follicles (NGFs) that are responsible for reproduction. A computer assisted approach to overcome the problems associated with manual microscopic analysis of ovarian reproductive tissues could be beneficial in increasing the accuracy and speed of the analysis. Few studies have reported on the use of images and other artificial intelligence techniques for ovarian tissue samples and have mostly concentrated on the analysis of cancer cells or ovarian animal tissues which are different from human ovarian reproductive tissues. Other studies using human ovarian reproductive tissues have been limited in terms of accuracy. This research examines the possibility of developing an automated computer approach which will improve the practices of these pathology laboratories to analyse female ovarian reproductive tissues and assist medical practitioners to provide necessary fertility treatment. The objective of the research was to study existing computerized methods used in various tissue assessments; identify the gaps and limitations; and to propose a novel method on digitized colour images acquired from ovarian reproductive tissue slides. The following major research question has been addressed by the research study: “How to develop an automated approach to assist pathology experts to identify ovarian reproductive NGFs (Non-growing follicles) or simply ovarian reproductive tissues using digital images acquired from type P63 (counter and non-counter stained) histopathology ovarian biopsy slides?” In order to answer this question, the research was carried out in a number of phases to examine existing computerized techniques for impact assessment of the ovarian reproductive tissue analysis. The research used a mixed method approach based on a case study using experimental and engineering methodologies. The study also employed quantitative and statistical data analysis methods. The research was carried out as a series of research activities including data collection, image processing, development of proposed approach, assessment factors (different magnification and different stains), validation of results with manual microscopic analysis results and development of the framework. A series of 7 different approaches were examined which started with basic image analysis technique. Modification and further medications were carried out to find the best possible approach which maintains the “gold standard” criteria in comparison to manual microscopic analysis results. A novel proposed approach was developed which used two phases: (1) phase one include pre-processing (intensity correction, filter operation, colour image segmentation, intensity clustering, feature extraction approach to find out the most suitable features); and (2) phase two for identifications of potential ovarian NGFs using shape, size and colour features that were extracted in phase one. It was found that the accuracy rate was above 90% for all magnifications and stains used in this research study which maintains the “gold standard” criteria in comparison to manual microscopic analysis results. To increase the accuracy rate and to diminish the false error rate classification approach was incorporated. The proposed approach established the most effect techniques in comparison to existing available approaches. A novel intensity correction was proposed and incorporated at the beginning of pre-processing, fast reliable novel filter operation was developed and incorporated for filter operation, colour image segmentation was considered to use the colour features for identification of region of interest (ROIs) from other tissues, extraction of features to capture NGFs’ characteristics, and incorporation of domain knowledge to identify NGFs. Validation was carried out with experts’ manual microscopic analysis results and similar regions were analysed to minimize the experts’ observation variability issues to improve the accuracy rate. A prototype software tool was developed in MATLAB platform, which enables a non-expert to easily use and analyse the ovarian reproductive tissues without changing any processing parameter automatically by giving the image magnification and image type as input parameter. The proposed approach was found to reduce the time and effort required for the analysis without any human intervention. The novelty of the research is that the approach was fully automated; non-experts will be able to use this approach for analysis; and no change of processing parameter is essential for new image batch/batches. The approach was also accurate, reliable and provided repeatable results in comparison to manual microscopic analysis results. Further work could explore the modification of tissue parameters that could be used for other tissue analysis.
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Evgenije, Adžić. "Регулисани погон асинхроног мотора са минималним бројем сензора". Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2014. http://dx.doi.org/10.2298/NS20131223ADZIC.
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У тези су предложена два унапређена алгоритма управљањаасинхроним мотором у условима када је број сензора који се користи упогону минималан. Број сензора који се користи у повратној спрезиуправљачког алгоритма сведен је на само један струјни сензор којимери струју једносмерног међукола погонског инвертора. Предложенеметоде елиминишу карактеристично изобличење реконструисанихфазних струја и постижу бољи квалитет и перформансе управљања уодносу на конвенционалну методу. Сва аналитичка разматрања у тезису праћена одговарајућим експерименталним резултатима, којипотврђују ефикасност предложених метода управљања.U tezi su predložena dva unapređena algoritma upravljanjaasinhronim motorom u uslovima kada je broj senzora koji se koristi upogonu minimalan. Broj senzora koji se koristi u povratnoj spreziupravljačkog algoritma sveden je na samo jedan strujni senzor kojimeri struju jednosmernog međukola pogonskog invertora. Predloženemetode eliminišu karakteristično izobličenje rekonstruisanihfaznih struja i postižu bolji kvalitet i performanse upravljanja uodnosu na konvencionalnu metodu. Sva analitička razmatranja u tezisu praćena odgovarajućim eksperimentalnim rezultatima, kojipotvrđuju efikasnost predloženih metoda upravljanja.
This thesis proposes two improved and robust induction motor drive controlmethods, in the case when there is a minimal number of sensors forproviding feedback signals. Number of used sensors is reduced to only onecurrent sensor measuring the inverter dc-link current. Proposed methodscancels offset jitter-like waveform distortion present in the reconstructedmotor phase currents, and achieves higher quality and drive performanceregard to conventional current reconstruction mechanism. Effectivness of theproposed methods are verified on developed HIL (hardware-in-the-loop)platform and laboratory induction motor drive prototype.
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Bodnarova, Adriana. "Texture analysis for automatic visual inspection and flaw detection in textiles". Thesis, Queensland University of Technology, 2000.
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Yeh, Chi-Tein y 葉奇典. "Phase-shift holographic interferometry testing technique". Thesis, 1994. http://ndltd.ncl.edu.tw/handle/98414950459990425597.
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Huang, Ren-Chieh y 黃仁傑. "Shift Checking System Based on Micro Location Technique". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/xc6m45.
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碩士景文科技大學
電腦與通訊系碩士班
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ABSTRACT The first thing for office workers to go to work is to punch cards. The punching system is based on the old card type, bar code type, evolution to magnetic card type, and face fingerprint recognition. In response to the progress of micro-positioning technology, the research hopes to be based on BLE low-power Bluetooth. Beacon positioning and sensing technology, combined with the cloud system to establish an employee check-in-checking prototype system, will improve the company’s intelligent management and interaction with the main employee, in addition to improving the speed and automation of employee punching. Shift Checking System Based mainly includes the following modules,(1) Staff Data Buliding System : Binding employee wearable device name management .(2) Staff on duty signing System: Including staff identity comparison and sign-in condition settings. (3) Personal secretary System: Allows employees to query check-in and return data and query work to-do items. (4) Surveillance System: Including personnel entry and exit record information and site safety monitoring remind.(5) Duty check cloud server: Including employee account management server, sign-in and logout management server, work item management server, and place entry and exit management server. Preliminary experimental data show that the success rate of the system at the close range is relatively stable.
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Yeh, Pin Wei y 葉品維. "Shuffle-Mixing Random Number Generator with Circular Shift Addition Technique". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/89umg7.
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Kang, He-Qian y 康何謙. "Study of High-Sensitivity Near-Infrared Phase-Shift Detection Technique". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/02579040009599417613.
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碩士逢甲大學
電機工程學系
104
The purpose of this research is to develop the technique of high sensitivity near infrared phase shift detection technique by using the laser diode (LD), avalanche photodiode (APD) and auto gain control (AGC) circuit. We have the desired performance from the optics and electronics for the near infrared phase shift detection technique. The performance from the electro-optics APD and LD is achievable. The use of corner cube mirrors is helpful as increasing detection range of system. The near-infrared laser measurement system design and prototype are initially established, and we use the 980 nm wavelengths LD and Si APD and AGC to optimize the system, in which laser light signals have been accurately received in distance 100 cm. The system test results show that the laser oscillator frequency of transmitter is 9 KHz, the operation voltage of transceiver is 5V, detection range is 100cm, and signal magnification is 126 times. The system is easy to alignment and has high sensitivity.
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Li, Lingxi. "Light Scattering of Complex Particles: Application to the Time-Shift Technique". Phd thesis, 2020. https://tuprints.ulb.tu-darmstadt.de/14206/8/Dissertation_Lingxi_Li_ULB.pdf.
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Particles with complex shapes and compositions are omnipresent in industrial processes, such as encountered in the chemical, pharmaceutical, automobile and food industries. For instance colloidal drop, i.e. drop with solid particles dispersed in them, are inherent in the spray drying process used frequently in the food industry. Thus, in order to optimize such processes, there is a need to characterize these particles in terms of size, colloidal (solid particle) concentration, the size of the inclusions and possibly also velocity. The present study addresses this need for drop characterisation and concentrates on some particular examples of complex particles: drops with single embedded spheres; drops with single embedded platelets (e.g. aluminum flakes); and drops with multiple micro- or nanoparticle inclusions (colloidal suspension drops). The characterization of a homogeneous spheroidal particle has also been studied, serving as a validation and reference case.
This thesis focuses on the light scattering of complex particles and characterization of such particles with the time-shift measurement technique. Within the scope of this study, spheroidal drops, drops with single embedded flakes or spheres, and drops with multiple spherical inclusions have been studied. According to the shape, composition and the size parameter of the particle, corresponding simulation methods have been chosen to simulate the light scattering. The ray-tracing method has been used to investigate the light scattering properties of spheroidal drop by varying its aspect ratio, and drops with single embedded flakes or spheres by varying the position of the sphere and the orientation of the flake within the drop. For drops with multiple inclusions, the polarized Monte Carlo ray-tracing method as well as the discrete dipole approximation method are used to study its light scattering properties. In addition, the time-shift signals, which are generated when the particle falls through a highly focused Gaussian beam of the time-shift instrument, have been simulated for the drops mentioned before. The goal is to investigate if the time-shift technique is able to unequivocally detect whether a drop contains a spherical particle or not, or detect if the drop contains flake. The possibility to use the time-shift technique to estimate the volume concentration of the inclusions within the drop has been studied as well.
To validate the simulation results, corresponding experiments have been conducted to obtain the raw time-shift signals by using the time-shift instrument to measure pure water drops as well as the colloidal drops, which have multiple polystyrene latex nanoparticles embedded. During the measurement, the size and the volume concentration of the nanoparticles have been varied. Subsequently, comparison has been made between the measured and simulated time-shift signals to validate the simulation results. Through signal processing, the relative scattering strength from the inclusions has been evaluated from the measured time-shift signal to estimate the volume concentration of the inclusions. The size of the inclusions is estimated through evaluation the attenuation ratio of the time-shift signal.
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Xiang, Chu. "Wavelength shift keying technique to reduce four-wave mixing crosstalk in WDM". Thesis, 2000. http://hdl.handle.net/1911/17390.
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In low dispersion fibers, the four-wave mixing (FWM) spectrum is symmetric with respect to the zero-dispersion wavelength. This thesis analyzes a wavelength shift keying (WSK) technique, a modification of the standard wavelength division multiplexing (WDM) system. WSK uses symmetric wavelength assignment and balanced detection to cancel FWM crosstalk to first order. Error probabilities for both dispersion shifted fiber and non-zero dispersion shifted fiber were calculated using Gaussian approximation. WSK out-performs standard on-off WDM at all signal power levels and allows a larger bit rate-distance product for a given BER requirement. Four-Wave mixing in a long-haul transmission scenario was simulated in an experimental testbed. BER measurements compared well with the calculations and proved that WSK is indeed noise tolerant.
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Fu, David K. y 傅國貴. "A novel I-line phase shift mask(PSM) technique for submicrom T-Gate formation". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/32416835755814468953.
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碩士國立交通大學
材料科學與工程系
89
Submicron T-gate formation with I-line using phase shift mask (PSM) technique has become very attractive due to its low capital investment and high throughput for GaAs MMIC technology. In this thesis a novel submicron less 0.2μm T-gate technology using phase shift mask technique is report. The 8% half-tone PSM was selected for the definition of the isolated narrow space. Before lithography, 2000Å nitride film was deposited on the wafer. After I-line PSM exposure and RIE etch of the silicon nitride film, 0.25μm or less opening was formed on the nitride film. To further reduce the dimension of the opening, the wafer was then deposited addition 600Å and 900Å nitride and etched back using RIE without any mask. 0.2μm or less opening was formed on the wafer after the dry etch. The wafer was then coated with another layer of photoresist to form lift-off structure. This novel process is a high throughput T-gate I-line PSM process compared to conventional E-beam lithography technology for GaAs MMIC production.